Stable Isotope Forensics: From Victims' Bones to Matchstick Wood

Wolfram Meier-Augenstein, who wrote a landmark textbook on stable isotope forensic analysis, published a second edition of the book early this year. (Photo: Courtesy of Wolfram Meier-Augenstein)

At the most elemental levels of matter, from plants to water to even the very cells in our body, there are slight fluctuations in the atoms—a tiny variation in the number of neutrons in the nuclei.

These different varieties of hydrogen, carbon, nitrogen, carbon and sulfur are called isotopes. And they are a trove of forensic information that is only starting to be tapped in the 21st century.

Wolfram Meier-Augenstein, a German-born scientist working in the United Kingdom, has used the exacting analytical techniques to help identify murder victims, to trace illicit international goods, and even to show where a person lived over the course of their entire life. His work on high-profile cases has been an integral part of the burgeoning field.

Now Meier-Augenstein, of Robert Gordon University in Aberdeen, has published his second edition of what some may call a landmark text on the work, Stable Isotope Forensics, through John Wiley and Sons, Ltd.

The book outlines not only the possibilities of the science—but also its limitations. And while it is written for highly-trained scientists in forensic laboratories worldwide, it also contains rundowns of dramatic cases in which Meier-Augenstein’s work took on an integral role.

At its very core, isotope work is based on investigating the fundamental building blocks in nature, he explained to Forensic Magazine in recent email interviews.

THE ELEMENTARY VARIETIES

Isotopes are marked by their unique identifiers. Originally used in identifying natural oils and flavors in the 1990s, wider forensic contexts only came into play in the early 2000s, according to Meier-Augenstein. As technology has improved, it has become easier and less costly to differentiate between hydrogen’s three naturally occurring isotopes, or oxygen’s three, for instance.

Based on the number of publications, the most common current uses are still in food authentication, and environmental forensics. From checking whether vegetable oil was legitimately produced where the label says it’s from, to reconstructing a chemical timeline of a pollutant spill, the isotope matrix can provide clues otherwise invisible to the eye.

Drug analysis is also another forensic niche for isotopes, including analysis of counterfeit pharmaceuticals, and its use to prove doping in sports. The data, if done right, can show whether marijuana was grown in a humid region of Brazil, whether a sample of heroin is likely to have come from Southeast Asia, or even whether certain signatures in synthetic drugs point to particular labs.

Explosives from ammonium nitrate, to Semtex and a smorgasbord of other chemicals, have gone under the advanced analysis, known as isotope ratio mass spectrometry.

Other uses include archaeology, climate studies, and ecology, as well as wildlife forensics, according to Meier-Augenstein.

Wolfram Meier-Augenstein, a forensic scientist at Robert Gordon University in the U.K., works with a colleague in the laboratory preparing a tooth for isotope analysis. (Photo: Courtesy of Wolfram Meier-Augenstein)

YOU ARE WHAT YOU EAT

But perhaps the most dramatic use of isotopes has been shown in what it can say about the human body—and thus what it can provide to criminal investigations that may otherwise be grasping at straws.

“People are what they eat and the water they consume in whatever form, be it directly (as a beverage) or be it indirectly (in prepared food or as integral part of fruit and vegetables),” he said. “The timelines that can be established are based either on different turn-over rates (e.g., bone) or different formation/growth rates (e.g. hair and nails) or when tissue that does not remodel was formed (permanent teeth).”

Meier-Augenstein had a forensic hand in some of the highest-profile isotope breakthroughs yet. Among those cases:

A man who had been dumped at a hospital in Wales died shortly thereafter of stab wounds and an apparent beating, as described in the textbook. The man appeared Asian, and fingerprints established his identity through the Interpol database. But there was no official record of the person ever having entered the United Kingdom. The Gwent police came to Meier-Augenstein, who took a lock of hair from the victim. Together, the isotopes of Hydrogen-2, Carbon-13, Nirtogen-15 and Oxygen-18 provided a kind of chemical timeline. The hydrogen and oxygen analysis indicated he had only been living in the U.K. for about two months at the time of death. But the analysis revealed even more: before the U.K. appearance, he had lived about three months in Poland or the Ukraine, and for six to seven months before that in the Czech Republic or Germany. Criminal investigators eventually unearthed a criminal record from Germany, when he had been fingerprinted. Eventually, the parallel investigations in both laboratory and on the international stage determined the man was Vietnamese, and had been smuggled into the U.K. by a gang of drug runners. He had been forced to farm cannabis to pay off his debt—but was beaten to death when a rival gang stole his crop. Three Vietnamese men were ultimately convicted of manslaughter in connection with the death in 2008.

The infamous “Scissor Sisters” case featured some incisive work by Meier-Augenstein. A dismembered body turned up in a Dublin canal in 2005. The remains showed characteristics of being African or of Afro-American ancestry. The body was disfigured with strange carvings, including genital mutilation. There was no head, which made identification even more difficult. But investigators did have pubic hair and fingernails, among other biological samples. Meier-Augenstein and his laboratory performed the work, and they determined that the person had lived in Ireland for a long time, perhaps 6 years or more. But he had originated somewhere among a wide swath of the globe, from Brazil, to the Lesser Antilles, to the Horn Africa, to the United Arab Emirates, Yemen and Oman, or even the western coast of India. Taken together with the African features, however, the team determined it was most likely the person was originally from the Horn of Africa. The findings allowed police investigators, who had even sent a delegation to West Africa on the hunch the disfiguring cuts had been part of a ritual, to focus their leads. Eventually the remains were identified as a 39-year-old man originally from Kenya (on the Horn of Africa), and then to his girlfriend and her two daughters, Linda and Charlotte Mulhall, who were convicted of the killing.

A Pakistani national was sentenced to life in prison in England in 2012, after isotope work proved some of the abuse he had subjected his son to leading to the boy’s death. The father, Pazeer Ahmed, claimed he had been taking good care of his son in the months since they had left Pakistan, even when the boy was found dead in Wakefield. Ahmed even claimed he had made his son special chicken dinners that were his favorite. But Meier-Augenstein and the scientists went to the most elementary levels to check out the story. What they found, from the atoms in the femur, big toenail, a thumbnail, and a pieces of deep muscle, portrayed a different set of conditions entirely. The boy had a stable diet up to the time four months before his death. But the last two months had shown no protein intake at all. The investigation also determined independently that the boy and father had come to the U.K. four months before the death.

A person suspected of trying to burn evidence relating to a murder was cleared by the invisible isotopes through the technique, as outlined in the book. The night of the murder had been damp, so a number of unspent matches were found at the scene of the questionable fire. A search of the suspect’s house turned up matchboxes, which appeared to have been the source of the unlit matches. The analysis of Carbon-13 and Hydrogen-2 in the wood sticks of the matches, however, determined the suspect’s matchbox and the matches at the fire scene had no commonalities. The evidentiary tie was thrown out.

But Meier-Augenstein told Forensic Magazine that isotopes are not themselves the solution to a criminal case.

“As I never tire to point out, isotope signatures do not positively identify a person,” he said. “Isotopes signature may help to identify a person by providing information that helps directing/focusing investigations. I always compare this to the needle-in-a-haystack scenario. Isotope signatures will not find the needle in a haystack. However, they will reduce the haystack to a manageable size.”

A FORENSIC FRONTIER

The key to the isotope work, thus, is knowing how far the scientific conclusions can go. Not every analysis is a case-buster, Meier-Augenstein explains in the book. Included alongside the dramatic case histories are specific recommendations for how to set up a laboratory to do the work, down to the details of setting up the helium and power supply.

Benchmarks for stable isotopes have been established by the International Union of Pure and Applied Chemistry, or IUPAC, and its Commission on Isotopic Abundance and Atomic Weights, or CIAAW. Scales and standards have also been established by the International Atomic Energy Agency, the National Institute of Standards and Technology, and the European Commission’s Institute for Reference Materials and Measurement, among other agencies, Meier-Augenstein said.

One of the pitfalls of the promising techniques, he added, is the presence of “cowboy operators” who may not be generating reproducible data, making overstated claims, or who may be getting involved without proper understanding of the complexity of the elemental palette of stable isotopes. Another major hurdle to the work is lack of funding for systematic research and development, and the creation of a matrix-matched standards framework.

Finally, simply knowing more about how these different isotopes interact with one another and function could eventually improve our fundamental understanding of matter—at a crime scene, and beyond.

“As this understanding grows so will the application’s scope of this technique move from a comparative method to a method that will enable law enforcement to link, for example, a drug dealer to clandestine lab to supplier of key chemicals, and thus help unravel entire networks and criminal organizations even if they are based on individual cells where members of cell A know nothing about the members of cell B,” he said.

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